This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A157504 #7 Feb 22 2015 23:26:46 %S A157504 -1,-2,-7,-40,-301,-2856,-32299,-416816,-5892345,-86464000, %T A157504 -1177909711,-8944121088,349846341467,29237270702080,1585383533246925, %U A157504 78578098584541184,3843296406581515919,190784066705549623296 %N A157504 (det(I - M) - 1)/x where M_jk = (j*x)^k/k!. %F A157504 E.g.f.: (det(I - M) - 1)/x where M_jk = (j*x)^k/k!. %F A157504 a(n) = A157503(n)/n. %Y A157504 Cf. A157503. %K A157504 easy,sign %O A157504 1,2 %A A157504 _Andrew J. Robbins_, Mar 02 2009